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freeCodeCamp/curriculum/challenges/chinese/04-data-visualization/data-visualization-with-d3/add-a-hover-effect-to-a-d3-element.md
Oliver Eyton-Williams ee1e8abd87 feat(curriculum): restore seed + solution to Chinese (#40683)
* feat(tools): add seed/solution restore script

* chore(curriculum): remove empty sections' markers

* chore(curriculum): add seed + solution to Chinese

* chore: remove old formatter

* fix: update getChallenges

parse translated challenges separately, without reference to the source

* chore(curriculum): add dashedName to English

* chore(curriculum): add dashedName to Chinese

* refactor: remove unused challenge property 'name'

* fix: relax dashedName requirement

* fix: stray tag

Remove stray `pre` tag from challenge file.

Signed-off-by: nhcarrigan <nhcarrigan@gmail.com>

Co-authored-by: nhcarrigan <nhcarrigan@gmail.com>
2021-01-12 19:31:00 -07:00

119 lines
2.5 KiB
Markdown

---
id: 587d7faa367417b2b2512bd4
title: 给 D3 元素添加悬停效果
challengeType: 6
forumTopicId: 301469
dashedName: add-a-hover-effect-to-a-d3-element
---
# --description--
我们可以为用户的鼠标悬停行为添加高亮显示的效果。到目前为止,矩形的样式应用了内置的 D3 和 SVG 方法,但是你也可以使用 CSS 来实现。
你可以使用 `attr()` 方法在 SVG 元素上设置 CSS 类。然后用 `:hover` 伪类为你新添加的 CSS 类设置鼠标悬停的效果。
# --instructions--
`attr()` 方法给所有的 `rect` 元素都添加 `bar` 类。当鼠标悬停在元素上时,它的 `fill` 将变为棕色。
# --hints--
`rect` 元素应该有 `bar` 类。
```js
assert($('rect').attr('class') == 'bar');
```
# --seed--
## --seed-contents--
```html
<style>
.bar:hover {
fill: brown;
}
</style>
<body>
<script>
const dataset = [12, 31, 22, 17, 25, 18, 29, 14, 9];
const w = 500;
const h = 100;
const svg = d3.select("body")
.append("svg")
.attr("width", w)
.attr("height", h);
svg.selectAll("rect")
.data(dataset)
.enter()
.append("rect")
.attr("x", (d, i) => i * 30)
.attr("y", (d, i) => h - 3 * d)
.attr("width", 25)
.attr("height", (d, i) => 3 * d)
.attr("fill", "navy")
// Add your code below this line
// Add your code above this line
svg.selectAll("text")
.data(dataset)
.enter()
.append("text")
.text((d) => d)
.attr("x", (d, i) => i * 30)
.attr("y", (d, i) => h - (3 * d) - 3);
</script>
</body>
```
# --solutions--
```html
<style>
.bar:hover {
fill: brown;
}
</style>
<body>
<script>
const dataset = [12, 31, 22, 17, 25, 18, 29, 14, 9];
const w = 500;
const h = 100;
const svg = d3.select("body")
.append("svg")
.attr("width", w)
.attr("height", h);
svg.selectAll("rect")
.data(dataset)
.enter()
.append("rect")
.attr("x", (d, i) => i * 30)
.attr("y", (d, i) => h - 3 * d)
.attr("width", 25)
.attr("height", (d, i) => 3 * d)
.attr("fill", "navy")
// Add your code below this line
.attr('class', 'bar')
// Add your code above this line
svg.selectAll("text")
.data(dataset)
.enter()
.append("text")
.text((d) => d)
.attr("x", (d, i) => i * 30)
.attr("y", (d, i) => h - (3 * d) - 3);
</script>
</body>
```